You have to respect his beliefs even if you're not ok with, he in his own right to have a beard and Oman air and Air Arabia are company from muslim countries, so if you not happy with that go back to home or if you are a national take it easy or move.
I'm very shocked by such a behavior it's like tomorrow everyone decide to impose to others his point of view, NO WAY, we have to respect each other and above all respect the integrity of each other even if we disagree the way of life of mr or miss ******, you can be atheist, jew, christian, muslim, whatever, it's up to you, but please keep you xenophobic comments for you.
Bye